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Subject: Re: [PATCH] clocksource/arm_global_timer: reconfigure clockevents after cpufreq change
From: Alexander Kochetkov <al.kochet@gmail.com>
In-Reply-To: <alpine.DEB.2.20.1611291432290.4358@nanos>
Date: Tue, 29 Nov 2016 17:05:19 +0300
Cc: LKML <linux-kernel@vger.kernel.org>,
        LAK <linux-arm-kernel@lists.infradead.org>, kernel@stlinux.com,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Patrice Chotard <patrice.chotard@st.com>,
        Marc Zyngier <marc.zyngier@arm.com>,
        Mark Rutland <mark.rutland@arm.com>
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References: <1480421716-30782-1-git-send-email-al.kochet@gmail.com> <1480421716-30782-2-git-send-email-al.kochet@gmail.com> <alpine.DEB.2.20.1611291432290.4358@nanos>
To: Thomas Gleixner <tglx@linutronix.de>
Sender: linux-kernel-owner@vger.kernel.org
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Hello Thomas!

> 29 нояб. 2016 г., в 16:42, Thomas Gleixner <tglx@linutronix.de> написал(а):
> 
> The frequency change would not only affect the clockevent device, it also
> would affect the clocksource. So the patch is incomplete, but see below.
Looks like kernel disallow change clocksource and shed_clock rate at
runtime. I haven’t found any function for that.

> 29 нояб. 2016 г., в 16:42, Thomas Gleixner <tglx@linutronix.de> написал(а):
> 
> That's broken and the clk framework should keep the CORE_PERI clock at a
> constant rate by reprogramming the divider of the CPU clock.

Thank you for the hint.

> Assumptions w/o real impact are a perfect reason not to apply that
> patch. This want's a proper proof that the global timer really changes and
> this hackery is required, which I seriously doubt.

It really changes. It changes like it changes for smp-twd. I guess they are
driven by same clock CORE_PERI.

Thank you for help.

Alexander.